U.S. Rep. Paul Ryan has called on Health and Human Services Secretary Kathleen Sebelius to resign over technical problems plaguing the federal health care exchange.

The Wisconsin Republican said Sebelius should step down during a phone conversation with Virginia Attorney General Ken Cuccinelli, who's running for governor and also wants the secretary ousted.

Ryan recalled Sebelius' earlier testimony to lawmakers that "the rollout was going to be almost flawless."

Ryan, who's chairman of the House Budget Committee, also released a letter Wednesday asking Sebelius to detail the costs of the "tech surge" the Obama administration says will fix the system and criticizing her for not responding to his earlier requests for her to testify before his committee.

"The American people have a right to know how your department intends to manage this large, complex program," Ryan wrote. Your continued silence on these important inquiries after refusing to testify raises serious questions about the administration's commitment to transparency and accountability."

Sebelius' office did not response directly to Ryan's comments or letter but said she "fully intends" to testify before Congress next week.